Evaporator for refrigerating plants



'- 5- R. BERNAT E1 AL EVAPORATOR FOR REFRIGERATING PLANTS Filed June 7, 193a Patented Dec. 24, 1935 UNITED STATES PATENT OFFICE EVAPORATOR FOR REFRIGERATING PLANTS Raoul Bernat and Henri Bernat, Bordeaux,

France 2 Claims.

This invention relates to evaporators used in refrigerating machines.

It is an object of the invention to provide a vertical arrangement for two sets of tubes. One 5 of the sets of tubes is exposed while the other set is positioned in a, vertically disposed tank which is filled with a low freezing liquid which acts as a reservoir when the refrigerator is in operation and absorbs heat when the refrigerator is stopped.

A further object of the invention is to provide means for forcing any oil into an upper receiver which may accumulate in a lower receiver.

It is also an object of the present invention to I provide means for creating a vacuum whereby the oil accumulated in the upper tank is extracted and returned in suitable amounts to the suction circuit.

A still further object of the invention is the formation of the sets of tubes into a grate formation, utilizing only two weldings.

With the above and other objects which will become apparent as the description proceeds, the invention comprises the arrangement and combination of parts as set forth in detail below, claimed in the claims and shown in the drawing,

' in which ti Figure 1 is a diagrammatic view of the inven- Figure 2 shows a front elevational view of a set of three tubes,

Figure 3 shows an exploded perspective view of portions of two tubes prior to assembly,

Figure 4 is a sectional view on the section line IV-IV of Figure 2, and

Figure 5 shows a detail view of the flap valve housing.

Referring to the drawing, the evaporator comprises the two receivers I and 2 between which extend the sets of tubes 3, 4 and 5 upon one side and the sets of tubes 6, I and 8 upon the other side, which latter tubes are contained in a tank 9.

Referring to Figure 2, each set of tubes comprises a main tube 8 upon which is welded a tube 2| which is bent in the form shown. Before welding, suitably shaped openings are provided in the tubes 8 and 2I (see Figure 3). These openings are brought into register and then the welding is carried out while held in the position shown in Figure 4. It will be noted that the tube 8 is slightly offset rearwardly in relation to the plane of the tube 2I. I

The liquefied gas is led from the condenser by means of the pipe ID, the end of which extends into the pipe I I which latter pipe is of a substan- (Cl. 62-126) I tially larger diameter whereby a substantially annular space is provided between the telescoped ends of pipes I and II.

The liquid when expanding causes the formation of a certain amount of vapor so that both liquid and gas will be conveyed into the receiver I by means of the pipe I2. Under these conditions the oil which maybe carried by the liquefied gas entering the evaporator is expelled into the receiver I. In addition, if oil should accumulate in the receiver or tank 2 while the refrigerator is not in operation, then such oil would penetrate into the annular space between pipes I0 and II and this oil would also be carried by pipe I2 into receiver I.

Inside the upper part of the receiver or tank I there is provided a suction pipe I3 and a flap valve assembly. A valve I5 is located in the conduit connecting the suction pipe I3 and the housing It for the flap valve. A pipe I6 connects the evaporator with the suction end of the compressor through the assembly I4.

As shown in Figure 1 particularly, the upper ends of the sets of tubes 3, 4, 5, 6, I and 8 open into the receiver I at a. higher level than the lower opening of the pipe I3. The oil carried up through pipe I2 consequently accumulates at the base of the receiver or tank I.

.The flap valve I9 is provided with vanes I1 and is of sufficient weight to create a difference in pressure of about 50 grs. per sq. cm. between the receiver I and the conduit I6. A suflicient value must be given to this difference in pressure so as to cause a suction of the oil accumulated at the base of the receiver I and then return it to the suction circuit.

The purpose of the valve I5 is to permit a free passage only to oil in the suction conduit. This valve cannot be dispensed with since it prevents large amounts of the liquid from flooding the compressor and thereby causing dangerous shocks. The flap valve I9 is provided with a lower spring I8 upon which the valve rests by means of the vanes I I and an upper spring 28. The springs enable a noiseless operation of the valve.

The arrangement illustrated between pipes I0 and II for leading the oil from the lower receiver 2 to the upper receiver I facilitates greatly the entrainment of the oil during operation and also permits avoiding operating without oil when the apparatus is not functioning. As a matter of fact, during the stopping of the machine the lubricant fills the annular space in the telescope portiofns of the pipes I0 and II and as soon as the I machine is placed in operation the lubricant is entrained.

The suction pipe I! opens at the lower 'part'oi the tank I as is clearly shown in Figure 1. Due

sure being maintained in the pipe I6 and consequently there is assured the entrainment of a constant quantity 01' gas and liquid. Due to this arrangement it is possible to avoid a sharp influx of liquid which would cause variations in the installation.

From the construction above described it is obvious also that if we assume a pressure p in the suction pipe l3 for the liquid, then the pressure P in the chamber ll of the flap valve construction and in the conduit I6 is highenthan the pressure in the suction pipe l3. In fact, a restricting element is formed by the cock valve I I being interposed between the gas exhaust conduit and the chamber M. This element l5 produces a fall in pressure tanks to which there is obtained an automatic regulation of the quantity of liquid suctioned.

Having .now particularly described and ascertained the nature oi. our invention and in what manner the same is to be performed, we declare that what we claim is:

1. An evaporator comprising an upper receiver, a lower receiver, pipes connecting said receivers and having their openings in the upper receiver located at a level above the bottom oi! said receive a first conduit connected to said lower receiver for leading liquefied gas thereto and terminating within said receiver and a second conduit connecting said lower receiver to said upper receiver and encircling the end of said first conduit for a portion of its length and spaced therefrom to provide a space between said conduits for the passage of liquid.

2. An evaporator comprising an upper receiver, a lower receiver, pipes connecting said receivers and having their openings in the upper receiver located at a level above the bottom of said receiver, a gas discharge conduit located in said upper receiver and having an opening located at the lower portion'of said receiver, a flap valve communicating with said upper receiver in said gas discharge conduit and a restricting element upon said gas discharge conduit located between the opening thereof and said flap valve.

' RAOUL BERNA'I'.

HENRI BERNAT. 

